/*
 * fsm.c - {Link, IP} Control Protocol Finite State Machine.
 *
 * Copyright (c) 1984-2000 Carnegie Mellon University. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The name "Carnegie Mellon University" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For permission or any legal
 *    details, please contact
 *      Office of Technology Transfer
 *      Carnegie Mellon University
 *      5000 Forbes Avenue
 *      Pittsburgh, PA  15213-3890
 *      (412) 268-4387, fax: (412) 268-7395
 *      tech-transfer@andrew.cmu.edu
 *
 * 4. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by Computing Services
 *     at Carnegie Mellon University (http://www.cmu.edu/computing/)."
 *
 * CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
 * FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "netif/ppp/ppp_opts.h"
#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */

/*
 * @todo:
 * Randomize fsm id on link/init.
 * Deal with variable outgoing MTU.
 */

#if 0 /* UNUSED */
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#endif /* UNUSED */

#include "netif/ppp/ppp_impl.h"

#include "netif/ppp/fsm.h"

static void fsm_timeout(void *);
static void fsm_rconfreq(fsm *f, u_char id, u_char *inp, int len);
static void fsm_rconfack(fsm *f, int id, u_char *inp, int len);
static void fsm_rconfnakrej(fsm *f, int code, int id, u_char *inp, int len);
static void fsm_rtermreq(fsm *f, int id, u_char *p, int len);
static void fsm_rtermack(fsm *f);
static void fsm_rcoderej(fsm *f, u_char *inp, int len);
static void fsm_sconfreq(fsm *f, int retransmit);

#define PROTO_NAME(f) ((f)->callbacks->proto_name)

/*
 * fsm_init - Initialize fsm.
 *
 * Initialize fsm state.
 */
void fsm_init(fsm *f)
{
    ppp_pcb *pcb = f->pcb;
    f->state = PPP_FSM_INITIAL;
    f->flags = 0;
    f->id = 0; /* XXX Start with random id? */
    f->maxnakloops = pcb->settings.fsm_max_nak_loops;
    f->term_reason_len = 0;
}

/*
 * fsm_lowerup - The lower layer is up.
 */
void fsm_lowerup(fsm *f)
{
    switch (f->state) {
        case PPP_FSM_INITIAL:
            f->state = PPP_FSM_CLOSED;
            break;

        case PPP_FSM_STARTING:
            if (f->flags & OPT_SILENT) {
                f->state = PPP_FSM_STOPPED;
            } else {
                /* Send an initial configure-request */
                fsm_sconfreq(f, 0);
                f->state = PPP_FSM_REQSENT;
            }

            break;

        default:
            FSMDEBUG(("%s: Up event in state %d!", PROTO_NAME(f), f->state));
            /* no break */
    }
}

/*
 * fsm_lowerdown - The lower layer is down.
 *
 * Cancel all timeouts and inform upper layers.
 */
void fsm_lowerdown(fsm *f)
{
    switch (f->state) {
        case PPP_FSM_CLOSED:
            f->state = PPP_FSM_INITIAL;
            break;

        case PPP_FSM_STOPPED:
            f->state = PPP_FSM_STARTING;

            if (f->callbacks->starting) {
                (*f->callbacks->starting)(f);
            }

            break;

        case PPP_FSM_CLOSING:
            f->state = PPP_FSM_INITIAL;
            UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
            break;

        case PPP_FSM_STOPPING:
        case PPP_FSM_REQSENT:
        case PPP_FSM_ACKRCVD:
        case PPP_FSM_ACKSENT:
            f->state = PPP_FSM_STARTING;
            UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
            break;

        case PPP_FSM_OPENED:
            if (f->callbacks->down) {
                (*f->callbacks->down)(f);
            }

            f->state = PPP_FSM_STARTING;
            break;

        default:
            FSMDEBUG(("%s: Down event in state %d!", PROTO_NAME(f), f->state));
            /* no break */
    }
}

/*
 * fsm_open - Link is allowed to come up.
 */
void fsm_open(fsm *f)
{
    switch (f->state) {
        case PPP_FSM_INITIAL:
            f->state = PPP_FSM_STARTING;

            if (f->callbacks->starting) {
                (*f->callbacks->starting)(f);
            }

            break;

        case PPP_FSM_CLOSED:
            if (f->flags & OPT_SILENT) {
                f->state = PPP_FSM_STOPPED;
            } else {
                /* Send an initial configure-request */
                fsm_sconfreq(f, 0);
                f->state = PPP_FSM_REQSENT;
            }

            break;

        case PPP_FSM_CLOSING:
            f->state = PPP_FSM_STOPPING;

        /* fall through */
        /* no break */
        case PPP_FSM_STOPPED:
        case PPP_FSM_OPENED:
            if (f->flags & OPT_RESTART) {
                fsm_lowerdown(f);
                fsm_lowerup(f);
            }

            break;

        default:
            break;
    }
}

/*
 * terminate_layer - Start process of shutting down the FSM
 *
 * Cancel any timeout running, notify upper layers we're done, and
 * send a terminate-request message as configured.
 */
static void terminate_layer(fsm *f, int nextstate)
{
    ppp_pcb *pcb = f->pcb;

    if (f->state != PPP_FSM_OPENED) {
        UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
    } else if (f->callbacks->down) {
        (*f->callbacks->down)(f); /* Inform upper layers we're down */
    }

    /* Init restart counter and send Terminate-Request */
    f->retransmits = pcb->settings.fsm_max_term_transmits;
    fsm_sdata(f, TERMREQ, f->reqid = ++f->id,
              (const u_char *)f->term_reason, f->term_reason_len);

    if (f->retransmits == 0) {
        /*
         * User asked for no terminate requests at all; just close it.
         * We've already fired off one Terminate-Request just to be nice
         * to the peer, but we're not going to wait for a reply.
         */
        f->state = nextstate == PPP_FSM_CLOSING ? PPP_FSM_CLOSED : PPP_FSM_STOPPED;

        if (f->callbacks->finished) {
            (*f->callbacks->finished)(f);
        }

        return;
    }

    TIMEOUT(fsm_timeout, f, pcb->settings.fsm_timeout_time);
    --f->retransmits;

    f->state = nextstate;
}

/*
 * fsm_close - Start closing connection.
 *
 * Cancel timeouts and either initiate close or possibly go directly to
 * the PPP_FSM_CLOSED state.
 */
void fsm_close(fsm *f, const char *reason)
{
    f->term_reason = reason;
    f->term_reason_len = (reason == NULL ? 0 : (u8_t)LWIP_MIN(strlen(reason), 0xFF));

    switch (f->state) {
        case PPP_FSM_STARTING:
            f->state = PPP_FSM_INITIAL;
            break;

        case PPP_FSM_STOPPED:
            f->state = PPP_FSM_CLOSED;
            break;

        case PPP_FSM_STOPPING:
            f->state = PPP_FSM_CLOSING;
            break;

        case PPP_FSM_REQSENT:
        case PPP_FSM_ACKRCVD:
        case PPP_FSM_ACKSENT:
        case PPP_FSM_OPENED:
            terminate_layer(f, PPP_FSM_CLOSING);
            break;

        default:
            break;
    }
}

/*
 * fsm_timeout - Timeout expired.
 */
static void fsm_timeout(void *arg)
{
    fsm *f = (fsm *)arg;
    ppp_pcb *pcb = f->pcb;

    switch (f->state) {
        case PPP_FSM_CLOSING:
        case PPP_FSM_STOPPING:
            if (f->retransmits <= 0) {
                /*
                 * We've waited for an ack long enough.  Peer probably heard us.
                 */
                f->state = (f->state == PPP_FSM_CLOSING) ? PPP_FSM_CLOSED : PPP_FSM_STOPPED;

                if (f->callbacks->finished) {
                    (*f->callbacks->finished)(f);
                }
            } else {
                /* Send Terminate-Request */
                fsm_sdata(f, TERMREQ, f->reqid = ++f->id,
                          (const u_char *)f->term_reason, f->term_reason_len);
                TIMEOUT(fsm_timeout, f, pcb->settings.fsm_timeout_time);
                --f->retransmits;
            }

            break;

        case PPP_FSM_REQSENT:
        case PPP_FSM_ACKRCVD:
        case PPP_FSM_ACKSENT:
            if (f->retransmits <= 0) {
                ppp_warn("%s: timeout sending Config-Requests", PROTO_NAME(f));
                f->state = PPP_FSM_STOPPED;

                if ((f->flags & OPT_PASSIVE) == 0 && f->callbacks->finished) {
                    (*f->callbacks->finished)(f);
                }

            } else {
                /* Retransmit the configure-request */
                if (f->callbacks->retransmit) {
                    (*f->callbacks->retransmit)(f);
                }

                fsm_sconfreq(f, 1); /* Re-send Configure-Request */

                if (f->state == PPP_FSM_ACKRCVD) {
                    f->state = PPP_FSM_REQSENT;
                }
            }

            break;

        default:
            FSMDEBUG(("%s: Timeout event in state %d!", PROTO_NAME(f), f->state));
            /* no break */
    }
}

/*
 * fsm_input - Input packet.
 */
void fsm_input(fsm *f, u_char *inpacket, int l)
{
    u_char *inp;
    u_char code, id;
    int len;

    /*
     * Parse header (code, id and length).
     * If packet too short, drop it.
     */
    inp = inpacket;

    if (l < HEADERLEN) {
        FSMDEBUG(("fsm_input(%x): Rcvd short header.", f->protocol));
        return;
    }

    GETCHAR(code, inp);
    GETCHAR(id, inp);
    GETSHORT(len, inp);

    if (len < HEADERLEN) {
        FSMDEBUG(("fsm_input(%x): Rcvd illegal length.", f->protocol));
        return;
    }

    if (len > l) {
        FSMDEBUG(("fsm_input(%x): Rcvd short packet.", f->protocol));
        return;
    }

    len -= HEADERLEN; /* subtract header length */

    if (f->state == PPP_FSM_INITIAL || f->state == PPP_FSM_STARTING) {
        FSMDEBUG(("fsm_input(%x): Rcvd packet in state %d.",
                  f->protocol, f->state));
        return;
    }

    /*
     * Action depends on code.
     */
    switch (code) {
        case CONFREQ:
            fsm_rconfreq(f, id, inp, len);
            break;

        case CONFACK:
            fsm_rconfack(f, id, inp, len);
            break;

        case CONFNAK:
        case CONFREJ:
            fsm_rconfnakrej(f, code, id, inp, len);
            break;

        case TERMREQ:
            fsm_rtermreq(f, id, inp, len);
            break;

        case TERMACK:
            fsm_rtermack(f);
            break;

        case CODEREJ:
            fsm_rcoderej(f, inp, len);
            break;

        default:
            if (!f->callbacks->extcode || !(*f->callbacks->extcode)(f, code, id, inp, len)) {
                fsm_sdata(f, CODEREJ, ++f->id, inpacket, len + HEADERLEN);
            }

            break;
    }
}

/*
 * fsm_rconfreq - Receive Configure-Request.
 */
static void fsm_rconfreq(fsm *f, u_char id, u_char *inp, int len)
{
    int code, reject_if_disagree;

    switch (f->state) {
        case PPP_FSM_CLOSED:
            /* Go away, we're closed */
            fsm_sdata(f, TERMACK, id, NULL, 0);
            return;

        case PPP_FSM_CLOSING:
        case PPP_FSM_STOPPING:
            return;

        case PPP_FSM_OPENED:

            /* Go down and restart negotiation */
            if (f->callbacks->down) {
                (*f->callbacks->down)(f); /* Inform upper layers */
            }

            fsm_sconfreq(f, 0); /* Send initial Configure-Request */
            f->state = PPP_FSM_REQSENT;
            break;

        case PPP_FSM_STOPPED:
            /* Negotiation started by our peer */
            fsm_sconfreq(f, 0); /* Send initial Configure-Request */
            f->state = PPP_FSM_REQSENT;
            break;

        default:
            break;
    }

    /*
     * Pass the requested configuration options
     * to protocol-specific code for checking.
     */
    if (f->callbacks->reqci) /* Check CI */
    {
        reject_if_disagree = (f->nakloops >= f->maxnakloops);
        code = (*f->callbacks->reqci)(f, inp, &len, reject_if_disagree);
    } else if (len) {
        code = CONFREJ; /* Reject all CI */
    } else {
        code = CONFACK;
    }

    /* send the Ack, Nak or Rej to the peer */
    fsm_sdata(f, code, id, inp, len);

    if (code == CONFACK) {
        if (f->state == PPP_FSM_ACKRCVD) {
            UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
            f->state = PPP_FSM_OPENED;

            if (f->callbacks->up) {
                (*f->callbacks->up)(f); /* Inform upper layers */
            }
        } else {
            f->state = PPP_FSM_ACKSENT;
        }

        f->nakloops = 0;

    } else {
        /* we sent CONFACK or CONFREJ */
        if (f->state != PPP_FSM_ACKRCVD) {
            f->state = PPP_FSM_REQSENT;
        }

        if (code == CONFNAK) {
            ++f->nakloops;
        }
    }
}

/*
 * fsm_rconfack - Receive Configure-Ack.
 */
static void fsm_rconfack(fsm *f, int id, u_char *inp, int len)
{
    ppp_pcb *pcb = f->pcb;

    if (id != f->reqid || f->seen_ack) /* Expected id? */
    {
        return; /* Nope, toss... */
    }

    if (!(f->callbacks->ackci ? (*f->callbacks->ackci)(f, inp, len) :
                                (len == 0))) {
        /* Ack is bad - ignore it */
        ppp_error("Received bad configure-ack: %P", inp, len);
        return;
    }

    f->seen_ack = 1;
    f->rnakloops = 0;

    switch (f->state) {
        case PPP_FSM_CLOSED:
        case PPP_FSM_STOPPED:
            fsm_sdata(f, TERMACK, id, NULL, 0);
            break;

        case PPP_FSM_REQSENT:
            f->state = PPP_FSM_ACKRCVD;
            f->retransmits = pcb->settings.fsm_max_conf_req_transmits;
            break;

        case PPP_FSM_ACKRCVD:
            /* Huh? an extra valid Ack? oh well... */
            UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
            fsm_sconfreq(f, 0);
            f->state = PPP_FSM_REQSENT;
            break;

        case PPP_FSM_ACKSENT:
            UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
            f->state = PPP_FSM_OPENED;
            f->retransmits = pcb->settings.fsm_max_conf_req_transmits;

            if (f->callbacks->up) {
                (*f->callbacks->up)(f); /* Inform upper layers */
            }

            break;

        case PPP_FSM_OPENED:

            /* Go down and restart negotiation */
            if (f->callbacks->down) {
                (*f->callbacks->down)(f); /* Inform upper layers */
            }

            fsm_sconfreq(f, 0); /* Send initial Configure-Request */
            f->state = PPP_FSM_REQSENT;
            break;

        default:
            break;
    }
}

/*
 * fsm_rconfnakrej - Receive Configure-Nak or Configure-Reject.
 */
static void fsm_rconfnakrej(fsm *f, int code, int id, u_char *inp, int len)
{
    int ret;
    int treat_as_reject;

    if (id != f->reqid || f->seen_ack) /* Expected id? */
    {
        return; /* Nope, toss... */
    }

    if (code == CONFNAK) {
        ++f->rnakloops;
        treat_as_reject = (f->rnakloops >= f->maxnakloops);

        if (f->callbacks->nakci == NULL || !(ret = f->callbacks->nakci(f, inp, len, treat_as_reject))) {
            ppp_error("Received bad configure-nak: %P", inp, len);
            return;
        }
    } else {
        f->rnakloops = 0;

        if (f->callbacks->rejci == NULL || !(ret = f->callbacks->rejci(f, inp, len))) {
            ppp_error("Received bad configure-rej: %P", inp, len);
            return;
        }
    }

    f->seen_ack = 1;

    switch (f->state) {
        case PPP_FSM_CLOSED:
        case PPP_FSM_STOPPED:
            fsm_sdata(f, TERMACK, id, NULL, 0);
            break;

        case PPP_FSM_REQSENT:
        case PPP_FSM_ACKSENT:
            /* They didn't agree to what we wanted - try another request */
            UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */

            if (ret < 0) {
                f->state = PPP_FSM_STOPPED; /* kludge for stopping CCP */
            } else {
                fsm_sconfreq(f, 0); /* Send Configure-Request */
            }

            break;

        case PPP_FSM_ACKRCVD:
            /* Got a Nak/reject when we had already had an Ack?? oh well... */
            UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */
            fsm_sconfreq(f, 0);
            f->state = PPP_FSM_REQSENT;
            break;

        case PPP_FSM_OPENED:

            /* Go down and restart negotiation */
            if (f->callbacks->down) {
                (*f->callbacks->down)(f); /* Inform upper layers */
            }

            fsm_sconfreq(f, 0); /* Send initial Configure-Request */
            f->state = PPP_FSM_REQSENT;
            break;

        default:
            break;
    }
}

/*
 * fsm_rtermreq - Receive Terminate-Req.
 */
static void fsm_rtermreq(fsm *f, int id, u_char *p, int len)
{
    ppp_pcb *pcb = f->pcb;

    switch (f->state) {
        case PPP_FSM_ACKRCVD:
        case PPP_FSM_ACKSENT:
            f->state = PPP_FSM_REQSENT; /* Start over but keep trying */
            break;

        case PPP_FSM_OPENED:
            if (len > 0) {
                ppp_info("%s terminated by peer (%0.*v)", PROTO_NAME(f), len, p);
            } else {
                ppp_info("%s terminated by peer", PROTO_NAME(f));
            }

            f->retransmits = 0;
            f->state = PPP_FSM_STOPPING;

            if (f->callbacks->down) {
                (*f->callbacks->down)(f); /* Inform upper layers */
            }

            TIMEOUT(fsm_timeout, f, pcb->settings.fsm_timeout_time);
            break;

        default:
            break;
    }

    fsm_sdata(f, TERMACK, id, NULL, 0);
}

/*
 * fsm_rtermack - Receive Terminate-Ack.
 */
static void fsm_rtermack(fsm *f)
{
    switch (f->state) {
        case PPP_FSM_CLOSING:
            UNTIMEOUT(fsm_timeout, f);
            f->state = PPP_FSM_CLOSED;

            if (f->callbacks->finished) {
                (*f->callbacks->finished)(f);
            }

            break;

        case PPP_FSM_STOPPING:
            UNTIMEOUT(fsm_timeout, f);
            f->state = PPP_FSM_STOPPED;

            if (f->callbacks->finished) {
                (*f->callbacks->finished)(f);
            }

            break;

        case PPP_FSM_ACKRCVD:
            f->state = PPP_FSM_REQSENT;
            break;

        case PPP_FSM_OPENED:
            if (f->callbacks->down) {
                (*f->callbacks->down)(f); /* Inform upper layers */
            }

            fsm_sconfreq(f, 0);
            f->state = PPP_FSM_REQSENT;
            break;

        default:
            break;
    }
}

/*
 * fsm_rcoderej - Receive an Code-Reject.
 */
static void fsm_rcoderej(fsm *f, u_char *inp, int len)
{
    u_char code, id;

    if (len < HEADERLEN) {
        FSMDEBUG(("fsm_rcoderej: Rcvd short Code-Reject packet!"));
        return;
    }

    GETCHAR(code, inp);
    GETCHAR(id, inp);
    ppp_warn("%s: Rcvd Code-Reject for code %d, id %d", PROTO_NAME(f), code, id);

    if (f->state == PPP_FSM_ACKRCVD) {
        f->state = PPP_FSM_REQSENT;
    }
}

/*
 * fsm_protreject - Peer doesn't speak this protocol.
 *
 * Treat this as a catastrophic error (RXJ-).
 */
void fsm_protreject(fsm *f)
{
    switch (f->state) {
        case PPP_FSM_CLOSING:
            UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */

        /* fall through */
        /* no break */
        case PPP_FSM_CLOSED:
            f->state = PPP_FSM_CLOSED;

            if (f->callbacks->finished) {
                (*f->callbacks->finished)(f);
            }

            break;

        case PPP_FSM_STOPPING:
        case PPP_FSM_REQSENT:
        case PPP_FSM_ACKRCVD:
        case PPP_FSM_ACKSENT:
            UNTIMEOUT(fsm_timeout, f); /* Cancel timeout */

        /* fall through */
        /* no break */
        case PPP_FSM_STOPPED:
            f->state = PPP_FSM_STOPPED;

            if (f->callbacks->finished) {
                (*f->callbacks->finished)(f);
            }

            break;

        case PPP_FSM_OPENED:
            terminate_layer(f, PPP_FSM_STOPPING);
            break;

        default:
            FSMDEBUG(("%s: Protocol-reject event in state %d!",
                      PROTO_NAME(f), f->state));
            /* no break */
    }
}

/*
 * fsm_sconfreq - Send a Configure-Request.
 */
static void fsm_sconfreq(fsm *f, int retransmit)
{
    ppp_pcb *pcb = f->pcb;
    struct pbuf *p;
    u_char *outp;
    int cilen;

    if (f->state != PPP_FSM_REQSENT && f->state != PPP_FSM_ACKRCVD && f->state != PPP_FSM_ACKSENT) {
        /* Not currently negotiating - reset options */
        if (f->callbacks->resetci) {
            (*f->callbacks->resetci)(f);
        }

        f->nakloops = 0;
        f->rnakloops = 0;
    }

    if (!retransmit) {
        /* New request - reset retransmission counter, use new ID */
        f->retransmits = pcb->settings.fsm_max_conf_req_transmits;
        f->reqid = ++f->id;
    }

    f->seen_ack = 0;

    /*
     * Make up the request packet
     */
    if (f->callbacks->cilen && f->callbacks->addci) {
        cilen = (*f->callbacks->cilen)(f);

        if (cilen > pcb->peer_mru - HEADERLEN) {
            cilen = pcb->peer_mru - HEADERLEN;
        }
    } else {
        cilen = 0;
    }

    p = pbuf_alloc(PBUF_RAW, (u16_t)(cilen + HEADERLEN + PPP_HDRLEN), PPP_CTRL_PBUF_TYPE);

    if (NULL == p) {
        return;
    }

    if (p->tot_len != p->len) {
        pbuf_free(p);
        return;
    }

    /* send the request to our peer */
    outp = (u_char *)p->payload;
    MAKEHEADER(outp, f->protocol);
    PUTCHAR(CONFREQ, outp);
    PUTCHAR(f->reqid, outp);
    PUTSHORT(cilen + HEADERLEN, outp);

    if (cilen != 0) {
        (*f->callbacks->addci)(f, outp, &cilen);
        LWIP_ASSERT("cilen == p->len - HEADERLEN - PPP_HDRLEN", cilen == p->len - HEADERLEN - PPP_HDRLEN);
    }

    ppp_write(pcb, p);

    /* start the retransmit timer */
    --f->retransmits;
    TIMEOUT(fsm_timeout, f, pcb->settings.fsm_timeout_time);
}

/*
 * fsm_sdata - Send some data.
 *
 * Used for all packets sent to our peer by this module.
 */
void fsm_sdata(fsm *f, u_char code, u_char id, const u_char *data, int datalen)
{
    ppp_pcb *pcb = f->pcb;
    struct pbuf *p;
    u_char *outp;
    int outlen;

    /* Adjust length to be smaller than MTU */
    if (datalen > pcb->peer_mru - HEADERLEN) {
        datalen = pcb->peer_mru - HEADERLEN;
    }

    outlen = datalen + HEADERLEN;

    p = pbuf_alloc(PBUF_RAW, (u16_t)(outlen + PPP_HDRLEN), PPP_CTRL_PBUF_TYPE);

    if (NULL == p) {
        return;
    }

    if (p->tot_len != p->len) {
        pbuf_free(p);
        return;
    }

    outp = (u_char *)p->payload;

    if (datalen) /* && data != outp + PPP_HDRLEN + HEADERLEN)  -- was only for fsm_sconfreq() */
    {
        MEMCPY(outp + PPP_HDRLEN + HEADERLEN, data, datalen);
    }

    MAKEHEADER(outp, f->protocol);
    PUTCHAR(code, outp);
    PUTCHAR(id, outp);
    PUTSHORT(outlen, outp);
    ppp_write(pcb, p);
}

#endif /* PPP_SUPPORT */
